10.11.2015 0 COMMENTS
However, modest bone loss seen with aerobic training

by Nancy Walsh
Senior Staff Writer, MedPage Today

SEATTLE — Older adults who diet and exercise are more likely to experience bone loss if they engage in aerobic training than resistance training, a researcher reported here.

After 5 months, bone mineral density (BMD) showed a modest decrease among those in an aerobic training plus calorie restriction group at the total hip (-0.008 g/cm², 95% CI -0.012 to -0.003, P=0.02) and femoral neck (-0.007 g/cm², 95% CI -0.014 to 0.001, P=0.03) after adjustment for age, sex, baseline body mass index (BMI) and BMD, and weight loss, according to Kristen Beavers, PhD, of Wake Forest University in Winston-Salem, N.C., and colleagues.

In contrast, no change was seen in BMD for those participating in a resistance training plus calorie restriction program at the total hip (0.001 g/cm², 95% CI -0.003 to 0.006) or femoral neck (0.008 g/cm², 95% CI -0.000 to 0.016), she reported in a poster session at the American Society for Bone and Mineral Research meeting.

“Identification of weight loss therapies that minimize bone loss in the elderly is critical,” she said.

“When older individuals want to lose weight, typically one-quarter to one-third of the weight loss isn’t fat — it’s muscle and bone,” she told MedPage Today.

Treatment guidelines say that these patients should try to minimize bone and muscle loss when losing weight, and one approach is to try combining the weight loss with exercise, she explained.

In older adults in a weight-stable state, exercise can help build bone mass, but it isn’t known if bone mass would be lost during caloric restriction, she said.

Therefore, to see if the effects of two different types of exercise programs differentially influenced BMD in older adults, she and her colleagues compared outcomes from two randomized studies of calorie restriction and exercise among individuals, 65 and older, whose BMI was 27 kg/m² or higher.

Participants’ mean age was 69, two-thirds were women, and more than 80% were white. None had osteoporosis at baseline.

In one trial, the participants were randomized to a structured resistance training program in which three sets of 10 repetitions of eight upper and lower body exercises were done 3 days each week at 70% of one repetition maximum for 5 weeks, with or without calorie restriction of 600 calories per day.

In the second study, participants were randomized to an aerobic program which was conducted for 30 minutes at 65% to 70% heart rate reserve 4 days per week, with or without calorie restriction of 600 calories per day.

A total of 60 patients completed the aerobic program, while 63 completed the resistance program. In this analysis, only the effects of the two exercise plus calorie restriction groups were included.

All participants were given 1,200 mg of calcium and 1,600 IU of vitamin D.

At baseline and then at 5 months, BMD was measured with dual emission x-ray absorptiometry.

Compliance with the exercise program was excellent, with participants attending more than 80% of sessions in both groups. The average weight loss being 8.2% (95% CI 7.2-9.3) with the aerobic program and 5.7% (95% CI 4.6-6.7) with the resistance program.

No differential treatment effects were seen for the lumbar spine (P=0.78).

“These findings were encouraging, and warrant replication in a longer-term randomized study,” Beavers said.